The brake disc is actually called a rotor, and replacing the pads and rotors is a fairly easy fix. The cost of the repair will come down to parts and labor. Here's what you can expect to pay on average:

Parts= Brake pads $25-$100, and rotors $150-$200 depending on the quality of the parts.

Labor= 1.5-2 hours $150-$220 depending on the shop's hourly rate and the skill of the mechanic.